U.S. Pat. No. 3,960,550 discloses a process for recovering silver from a photographic film having a polymer base and a silver bearing emulsion layer coated thereon comprising immersing and washing the photographic film in a bleach solution of sodium hypochloride until the silver bearing emulsion layer is removed from the polymer base and disposed in said solution; introducing sodium hydroxide into said solution to precipitate said silver and adding a flocculating agent into said solution to settle said precipitate to a lower strata of said solution in the form of sludge; separating the sludge from the solution; drying and heating the sludge into a hard cake; pulverizing the cake and heating the pulverized cake to melt silver therefrom. In this process, a bleach solution is prepared for removing silver halides from the photographic film; in addition, several chemicals are utilized to obtain the silver containing sludge, which not only increase the silver recovering costs, but create additional pollutions.
U.S. Pat. No. 4,799,954 discloses a process for the recovery of silver from a photographic film comprising using a caustic alkali solution at elevated temperatures with high shear to remove silver halides from the film and reduce the silver halides to metallic silver; separating the silver containing solution from the film; and acidifying the silver containing solution to separate the metallic silver. This process also suffers the same disadvantages as those mentioned in U.S. Pat. No. 3,960,550, because several chemicals are required for recovering silver from the photographic film.
In developing photographic films or photographs, certain chemicals in the form of solution are used, and the waste solutions generated therefrom are detrimental to the environment, and thus require treatments before being discarded. Photographic development waste solutions are generally subjected to an electrolysis treatment for reducing silver ions contained therein to metallic silver, and then the electrolysis treated solutions are subjected to conventional waste water treatments to reduce the COD value and enhance the clarity.
An object of the present invention is to provide a process which can recover silver from a photographic film and a photographic development waste solution at the same time.
Another object of the present invention is to provide a process for separating a silver bearing emulsion layer from a photographic film, in which a photographic development waste solution is used to remove the silver bearing emulsion layer from the film.
Still another object of the present invention is to provide an improved process for recovering silver from a photographic development waste solution by electrolysis, in which a photographic film having a silver bearing emulsion layer coated thereon is immersed in the waste solution and the silver bearing emulsion layer is removed from the photographic film to the waste solution.